The present invention applies generally to the field of wrenches. In particular, the present invention provides an easy and safe means for turning otherwise difficult to turn valves with a circular spoked hand wheel.
In the petroleum and chemical industries it is frequently necessary to turn large valves. These valves can be extremely difficult to turn, and may become increasingly so with age. Wrenches can be attached to the valve wheel to provide greater leverage to rotate the wheel.
Various methods of aiding this process have been proposed. For example, U.S. Pat. No. 2,086,722 describes a wrench in which three projections extend from the main body of the wrench so as to engage the rim of the valve wheel. U.S. Pat. No. 2,539,262 describes a wrench that alternately wraps two members over and under the wheel rim in order to provide additional leverage. U.S. Pat. No. 2,682,189 provides a wrench that does so in an improved manner over '262.
The above-described devices have several inherent disadvantages. First, they are not is self-supporting upon being slipped onto the valve, so they are likely to cause injury when the wrench is released. Second, they do not derive support from both the spoke and the wheel rim, thereby more evenly distributing the load so as to minimize the chance of breakage. Further, they do not effectively eliminate the chance of slippage along the rim by positively and necessarily engaging the spoke of a valve wheel.